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Mar 30
Headshot of Marc Vermulst with name and title

Assistant Professor Marc Vermulst: the role of genetic mutations in human aging and disease

By COVID-19, Lifespan Health, Podcast, Research

Marc Vermulst, PhD, is an assistant professor of gerontology at the USC Leonard Davis School, who focuses on the role of genetic mutations in human aging and disease. He recently spoke to us about how his research into transcription errors, essentially copying mistakes, aims to strengthen vaccines and delay or prevent diseases.

On transcription errors

…when you go from DNA to a protein, there’s a short intermediate molecule that needs to be created, and that is an RNA molecule. And so conceivably you can make the wrong proteins … if a mistake occurs in the process of making an RNA molecule and that process is called transcription. So we study how frequently mistakes occur when RNA molecules are generated and what type of impact that has on aging and disease.

When I first started this project the reason why it hadn’t been studied much was because there was no technique capable of actually finding them, so it was something that we just could not see.  So what my lab did is was we designed a novel tool, a molecular biology tool, that allowed us to find these transcript errors across the entire genome. So it was this massive improvement, and suddenly we could observe things that were previously unobservable and what we discovered with it was that these errors are really, really frequent and when they happen, there are a couple of impacts that they have.

The most important one probably is that they result in incorrect proteins and those proteins tend to fold in the wrong way. Proteins are large 3D molecules. In order to function, this long molecule needs to fold in a particular structure. And when you make a mistake in the generation of that protein, because of a transcript error, the protein tends to misfold and as it turns out, misfolded proteins are a key component of numerous age-related diseases, including Alzheimer’s disease, Parkinson’s disease, amyotrophic lateral sclerosis. All of these diseases are caused by misfolded proteins. So, what I think that we really found is a new component of the etiology, the origin of all of these diseases.

… transcription errors occur a hundred to a thousandfold more frequently than genetic changes. So most of the mistakes that occur in proteins are not due to genetic changes, they are due to these transcript errors.

One of the things I’m really interested in is the occurrence of age-related diseases for example Alzheimer’s and Parkinson’s disease. And one of the major questions is why do people get these diseases? There are families that have a mutation that makes them more predisposed to getting these diseases, but that really only explains five to maybe 15% of all of the cases. The remaining 85 to 95%. We really have no clue why these people get these diseases. So what I’m trying to do is I’m trying to explain these remaining 85%.

Because all of these diseases are caused by misfolded proteins, and transcription errors cause these misfolded proteins, I think that we have found a new mechanism that can cause these diseases. And if the mechanism is indeed correct that means we can now do something about it. So it’s really about finding the origin of the disease itself in order to be able to design medicine for it. That’s one of the major goals. We’re also asking when aging actually happens.  We have reason to believe that the events that lead to aging can occur many, many years earlier, probably decades. And perhaps in certain cases, the pace of aging is actually set in our twenties or thirties. And that’s one of the things we’re trying to prove as well,

On COVID-19

… one of the reasons why viruses become resistant to vaccines or to drugs is because there is always one viral particle that happens to get a mutation that allows it to be resistant. So one of the major things people want to know about viral particles and different kinds of viruses is how fast do mutations accumulate in the genome of these viruses. And they want to do that for two different reasons. First of all, they want to know that because they want to be able to predict how quickly viruses might get resistance to certain treatments or vaccines. The higher the mutation rate, the faster that would happen. Secondly, they want to be able to predict what type of viruses might erupt in the future. So we now know that for example, that a coronavirus has a certain genetic composition, but that composition might be completely different next year or the year afterward. So by doing these mutational analyses, we’re able to predict hopefully what the virus might look like in the future. So we can better prepare for an outbreak in 2022 or 2023. It’s been a really rewarding project.  So the reason why I got into it is because of my interest in genetic mutations and that’s a key component of the viral particles.

We’ve used this super powerful big data tool to study how the virus mutates inside cells and we have a couple of different goals with it. First of all, we want to determine how quickly these mutations actually happen. Right? So that will give us an answer as to how quickly viral particles might come up with mutations that make it resistant to certain pigments and vaccines. And we’ve already heard in on the news that new mutant versions of the virus have come up, right. , it’s a strain from Brazil, there’s a strain from England that are more virulent and more dangerous and the initial coronavirus. So that is one of the consequences of the genetic changes.

The virus has a key protein that it needs to make in order to produce the envelope of the virus itself, all kinds of surface proteins and these proteins are essential. So certain genetic changes will destroy those proteins, and that will result in the death of the virus. So if we do a massive analysis of the entire genome of this virus, and we do that over time, what will find is that there are mutations present everywhere on the viral genome, except for those few spots where the mutation kills the actual virus.

So by virtue of looking at locations in the genome, or finding them where mutations do not occur, we can find these Achilles heels of the virus. And that would allow us to guide the development of vaccines to that specific spot. … if we target the vaccine to a spot that cannot be mutated, that means that the virus has two choices. It can either be destroyed by the vaccine or a treatment itself, and in an effort to try to get out of it, it could mutate that position of its genome, but in doing so, it will kill itself, so it’s a no win situation for the virus. That is one of the goals of this project also.

Feb 25
Headshot of Hussein Yassine with name and faculty title

Dr. Hussein Yassine: Uncovering links between nutrition, genes, and risk for Alzheimer’s disease

By Alzheimer's and Dementia, Lifespan Health, Podcast, Research

Dr. Hussein Yassine is a professor of medicine at the Keck School of Medicine at USC and is uncovering links between nutrition, genes, and risk for Alzheimer’s disease. He spoke to us about his research on APOE4, omega-3s and inflammation in the brain.

On APOE4 and Alzheimer’s risk

So APOE is a gene on chromosome 19. It exists in the population in three different forms. The two form, not very common, the three form, the most common and the four form, which makes about 20% of the population. The four form, if you get one copy from your parents, your chances of getting Alzheimer’s disease increased two to four times. If you inherit two copies, meaning you get one copy from mom and one copy from dad,  your chances of getting Alzheimer’s, or the odds ratio, goes to 12 times, meaning an APOE4 E4 homozygote, uh, 50% of those homozygotes by the age of 80 will have Alzheimer’s disease.

On the work of his lab

My lab is working to understand whether omega-3s can slow down cognitive decline in people at high risk of Alzheimer’s disease, based on APOE4. We are working on three different fronts. One, we have basic science models where we study the brains of APOE4 targeted replacement mice. We use brain imaging to study labeled DHA brain uptake in the human brain, and we do clinical trials where we give people omega-3 supplementation and look at outcomes.

On omega-3 supplements versus dietary interventions

At this point in time, we do not have high quality evidence to suggest that supplements make a difference. But we know from landmark observational cohorts, for example, the Framingham in the US, the Triple C in France, the Rotterdam in the Netherlands, and many others that people who consume at least one serving of fatty fish per week have lower risk of developing Alzheimer’s disease. In contrast trials that have involved omega-3 supplements have not panned out. And as we discussed, omega-3 supplements might be too late to be given to patients with neurodegeneration because they may not reverse neuronal death. Giving omega-3s to the general population may prove to be very difficult because the majority of people do not develop Alzheimer’s. So we need more research before we can recommend supplements. In addition, we don’t know exactly what kind of supplements we should be providing, the exact dose, the composition that duration. More research is needed to figure out those questions.

On what can people do to reduce Alzheimer’s disease risk

I think timing is key. I think if you know that you are at increased risk based on family history or APOE4 genotype  nutritional and lifestyle interventions during middle age will provide you likely the most benefit. Our research and others suggest that between the ages of 45 and 65, those at risk individuals should be on certain lifestyle modifications, whether it is at least one serving of fatty fish per week, or some good exercise regimen. We’re not talking about marathon running, maybe three times a week, 15 minutes per day is good enough. Lifestyle modifications, no smoking, reduced consumption of simple sugars to avoid complications of diabetes and obesity, increased intake of green leafy vegetables, which are enriched in polyphenols and antioxidants, good sleep, listening to music, certain forms of meditation, or in some individuals praying. And, uh, all of these factors, we know that have positive effect on mitigating or decreasing the chances of getting Alzheimer’s.

One additional factor that I did not discuss is hypertension or blood pressure control.  Blood pressure is known as a silent killer, because people have blood pressure, but they don’t know that they do so. Blood pressure control, diabetes control, cholesterol control in middle age together with these lifestyle changes can really pay dividends decades later. Once people start having symptoms and we’re talking now 60 to 80, they often come to us and they’re talking to us about omega-3 intake, about all these changes. And unfortunately at this time, the interventions are not very effective.

On the most important points  Dr. Yassine hopes people understand from  his research?

The biggest takeaway is that there is a life-course risk of Alzheimer’s disease risk in APOE4 carriers that starts shortly after birth. But mainly it takes decades before symptoms start. We know from imaging studies, between the ages of 20 all the way to 60, that the APOE4 brain is compensating to maintain cognition. Once this compensation fails, APOE4 carrier brains starts deteriorating, and you see signs of neurodegeneration and Alzheimer’s dementia. Our research emphasizes the importance of a healthy lifestyle, which includes sufficient omega-3 consumption, defined as at least one serving of fatty fish per week, lifestyle factors such as exercise, sleeping, music, meditation, family connections, combating depression, and social isolation, and social isolation is a problem now with COVID. And in addition to that, not smoking and reducing the amount of simple sugars consumed to reduce diabetes and cardiometabolic risk. Those interventions, we all know that they are critical, but our research suggests that there’s a critical time to do these interventions during middle age, to prevent the progression to Alzheimer’s at the age of 65 to 75. Once patients develop this disease, those interventions become less effective. So this is the greatest takeaway from the research we are doing.

On his message to young people

So my message to young people is that if you have a family history of Alzheimer’s disease, or that you know that you are an E4 carrier, plan in advance. Learn about the risks of Alzheimer’s disease, learn about the risks of carrying the APOE4 genotype and get informed, because we have cutting-edge research to help you out in preventing the risks of this disease early on.

On the importance of Alzheimer’s research

Up to 25% of individuals carry APOE4. So in a room of a hundred people, 25 people will have one copy of APOE4, that’s enormous. And they make the bulk, up to 50%, of patients with Alzheimer’s. We have so many APOE4 carriers in the community, and I think more research in this area is very important to the future of mitigating or changing the risk of Alzheimer’s disease. We should start early and we should try the best we can to prevent this disease because we know once it happens, it’s very difficult to treat.

On how to reach Dr. Yassine

If anybody listening to the podcast has family members with Alzheimer’s disease, they are concerned about being an APOE4 carrier and would require more advice or perhaps participate in any of our trials. Please feel free to email me. My email is hyassine@usc.edu, and you can look me up at the USC directory website and I’m happy to help.

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